Green fluorescent protein-like pigments optimize the internal light environment in symbiotic reef building corals
Abstract
Pigments homologous to the Green Fluorescent Protein (GFP) have been proposed to fine-tune the internal light microclimate of corals, facilitating photoacclimation of photosynthetic coral symbionts (Symbiodiniaceae) to life in different reef habitats and environmental conditions. However, direct measurements of the in vivo light conditions inside the coral tissue supporting this conclusion are lacking. Here, we quantified the intra-tissue spectral light environment of corals expressing GFP-like proteins from widely different light regimes. We focus on (1) photoconvertible red fluorescent proteins (pcRFPs), thought to enhance photosynthesis in mesophotic habitats via wavelength conversion, and (2) chromoproteins (CPs), which provide photoprotection to the symbionts in shallow water via light absorption. Optical microsensor measurements indicated that both pigment groups strongly alter the coral tissue light environment. Estimates derived from light spectra measured in pcRFP-containing corals showed that fluorescence emission can contribute to >50% of orange-red light available to the photosynthetic symbionts at mesophotic depths. We further show that upregulation of pink CPs in shallow-water corals during bleaching leads to a reduction of orange light by 10-20% compared to low-CP tissue. Thus, screening by CPs has an important role in mitigating the light-enhancing effect of coral tissue scattering during bleaching. Our results provide the first experimental quantification of the importance of GFP-like proteins in fine-tuning the light microclimate of corals during photoacclimation.
Data availability
Data used in this study is available from https://doi.org/10.5061/dryad.0gb5mkm1z
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Data from: Green fluorescent protein-like pigments optimize the internal light environment in symbiotic reef building coralsDryad Digital Repository, doi:10.5061/dryad.0gb5mkm1z.
Article and author information
Author details
Funding
H2020 European Research Council (702911-BioMIC-FUEL)
- Daniel Wangpraseurt
Gordon and Betty Moore Foundation (GMB 9325)
- Daniel Wangpraseurt
Gordon and Betty Moore Foundation (GBMF9206)
- Michael Kühl
Natural Environment Research Council (NE/S003533/2)
- Jörg Wiedenmann
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2022, Bollati et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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